In adjusting control parameters for a controller, there is available a method of determining optimal control parameters by repeating a series of procedures including a procedure of causing an operator to adjust control parameters by using his/her experience and knowledge, a procedure of actually controlling a controlled system by using the controller for which the parameters have been set, a procedure of detecting a controlled variable output from the controlled system in accordance with a manipulated variable output from the controller, and a procedure of comparing the controlled variable with a set point of control.
This method requires much labor and adjustment cost. In place of this method, therefore, the following procedure is also practiced: analyzing process parameters (a process gain, a process time constant, and the like) including the degree of a controlled system and determining control parameters. In this procedure, a modeling step of approximating a feature of the controlled system with a mathematical model is executed, and control parameters are determined by referring to the modeling result. Conventionally, however, this method requires expert speculation and operation, and hence everyone cannot use the method.
In consideration of such a situation, reference 1 (Japanese Patent Laid-Open No. 2004-38428) discloses a control parameter adjusting technique of automatically generating a mathematical model of a controlled system by acquiring the time-series data of a manipulated variable output from a controller to the controlled system and time-series data of a controlled variable output from the controlled system in accordance with the time-series data of the manipulated variable, and allowing easy adjustment of control parameters for the controller while checking control features obtained upon changing the control parameters in accordance with simulation using the mathematical model.